In recent years, with the advent of the era of cloud computing, high performance of Internet switches and routers and reduction in power consumption are urgent needs. Further, as a search engine of the Internet, one capable of reliably performing a search operation at a high speed with low power consumption has been sought. To respond to the request, in recent years, Internet switches and search engines using the CAM have been increased.
Here, in a typical CAM, search data called key data is input to a typical CAM when search of data stored in the CAM is performed. When the same data as the key data is stored in a memory, the CAM outputs an address called an entry address in which the key data is stored. Typically, to realize such a search function, an access to all memory spaces in the CAM is required, and thus, there has been a problem of not only complication of a circuit configuration but also an increase in the power consumption. Especially, the problem of an increase in the power consumption becomes increased with an increase in the scale of the CAM. Therefore, currently, it has become a serious problem.
To address the problem, Patent Literature 1 proposes a data search device for achieving low power consumption while making the most of a high-speed search performance of the CAM. The data search device of Patent Literature 1 newly orders a plurality of pieces of rule data in which priorities have been determined according to the order of size, and allocates the rule data to a plurality of memory blocks according to the order. Further, the search device designates one memory block to be searched and executes search processing when searching data. As described above, the data search device of Patent Literature 1 activates only the one designated block and does not need to activate other blocks when performing the search processing. Therefore, the data search device can reduce the power consumption to that extent at the time of search, compared with a normal CAM.